Vertical Underground Storage Tank and Method of Installing and Forming the Same

ABSTRACT

A vertical underground storage tank that is installed and partly in-situ formed with minimized excavation, minimum footprint, and without dewatering.

FIELD OF THE INVENTION

The present invention pertains to underground storage tanks. More specifically, the present invention provides a new type of vertical underground storage tank that is installed and partly in-situ formed with minimized excavation, minimum footprint, and without dewatering.

BACKGROUND OF THE INVENTION

Underground storage tanks have historically been used for the storage of fuel and hydrocarbons, such as gasoline, fuel oil, diesel oil, toxic fluids or various chemicals. Increasingly, such tanks are being used for rainwater harvesting for conservation and water quality control to comply with discharge regulations. Conventionally, underground storage tanks are cylindrical in shape with dome or egg-shaped end caps at either end of the cylinder and are placed horizontally in an open excavation ultimately backfilled to original grade. Recently, for rainwater harvesting such tanks are available in a variety of shapes, sizes, and materials.

The horizontal placement of the conventional underground storage tanks creates large footprint that limits their installation to locations on private land of sufficient size. The open excavation method involves digging, hauling, and backfilling of large volumes of soil that entails significant planning, permitting, time, and cost. In addition, there is the need for dewatering in locations of high groundwater, which requires special permit and incurs significant additional complexity, time, and cost.

Therefore, there is a need for an alternative underground storage tank that that is partly in-situ formed with minimized excavation, minimum footprint, and without dewatering.

SUMMARY OF THE INVENTION

The present invention provides a solution for the above stated need with a new type of underground storage tank that is configured for vertical placement to accomplish minimum footprint and excavation. The underground storage tank of the present invention is comprised of a vertical cylinder vessel installed inside a bored shaft of marginally larger dimeter and about the same length, in a male-female fitting arrangement, followed by concrete backfilling of the annulus. Therefore, the vertical tank of the present invention is a composite of an inner cylindrical vessel that may be made from a variety of material such as metal or plastic, encased in an outer shell of in-situ poured concrete having certain thickness. The inner vessel provides the vertical tank of the present invention with impermeability and controlled material specification for health and safety regulatory compliance, while the outer concrete encasement shell provides structural integrity and ballast against floatation in situations of high ground water. The vertical bored shaft serves both as the formwork for concrete encasement to create the concrete shell of the tank and the housing for the finished underground tank.

The vertical cylindrical tank of the present invention has provisions for access from the circular end at the top, which distinguishes it from existing cylindrical underground storage tanks that provide access from ground surface into the tank along the body of the cylinder. Also, the footprint of the vertical tank of the present invention is only as large as the diameter of the tank and does not increase with the length of the cylinder for larger storage volumes, which is in contrast to existing cylindrical underground storage tanks whose footprint increases with the length of the cylinder for larger storage volumes.

The boring of the vertical shaft of the present invention may be accomplished by a number of technologies that have been developed for constructing caissons for bridge piers, tunnel access, and mine ventilation. The technologies are capable of boring vertical shafts with large diameters and extensive lengths in a wide range of ground conditions, and can accommodate the requirements of the present invention.

The present invention can be utilized in a number of embodiments. In one embodiment, the present invention is a single vertical tank of certain length, diameter, end cap configuration, and composite wall thickness suitable for installation in unsaturated soil conditions above groundwater level. In another embodiment, the present invention is configured for installation in saturated soil conditions below groundwater level. In this embodiment, the inner vessel is fitted with a port near the bottom having an open/close mechanism that admits water in during lowering of the vessel inside the shaft. The port is then closed from the ground surface for concreting and the water inside the vessel is removed once the concrete is set, thus enabling installation without dewatering. In yet another embodiment the present invention is configured for installing a plurality of interconnected tanks. In this embodiment, a number of inner vessels are equipped with internal fittings that interconnect the vessels with underground pipes installed using horizontal boring techniques.

It is an object of this invention to provide a new type of vertical underground storage tank that is partly in-situ formed with minimized excavation, minimum footprint, and without dewatering.

It is an object of this invention to provide improved elements and arrangements by apparatus for the purposes described thereof, which is comparable in cost with existing systems, dependable, and fully effective in accomplishing its intended purposes.

These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cut section of one embodiment of the present invention for installation in unsaturated soils showing a vertical cylinder vessel ready for insertion inside a vertical bored underground shaft of marginally larger diameter and similar length.

FIG. 2 is a cut section of the same embodiment of the present invention as in FIG. 1 showing the vertical cylinder vessel inserted inside a vertical bored underground shaft of marginally larger diameter and similar length.

FIG. 3 is a cut section of the same embodiment of the present invention as in FIG. 1 showing a vertical storage tank comprised of a composite of an inner vessel and an outer concrete shell in position underground.

FIG. 4 is a cut section of another embodiment of the present invention for installation in saturated soil conditions showing a vertical cylinder vessel having a port near the bottom ready for insertion inside a vertical bored underground shaft of marginally larger diameter and similar length that is filled with groundwater.

FIG. 5 is a cut section through the vessel of the same embodiment of the present invention as in FIG. 4 showing the port near the bottom of the vessel equipped with an inflatable plug that serves as the open/close device for the port, in uninflated “open” position.

FIG. 6 is a cut section through the same embodiment of the present invention as in FIG. 4 showing the vertical cylinder vessel inserted inside a bored underground shaft of marginally larger diameter and similar length with the water in the shaft having entered the vessel.

FIG. 7 is a cut section through the same embodiment of the present invention as in FIG. 4 showing the water-filled vertical cylinder vessel inside an underground shaft having been concrete-encased, the vessel port having been closed prior to pouring of the concrete in the annuls to prevent its entry into the vessel.

FIG. 8 is a cut section through the embodiment of the present invention for installation in saturated soil conditions showing a concrete-encased vertical cylinder vessel installed and formed inside an underground shaft under the groundwater level with water having been removed from inside the vessel.

FIG. 9 is a cut section through the vessel of the same embodiment of the present invention as in FIG. 4 showing the port near the bottom of the vessel equipped with an inflatable plug that serves as the open/close device for the port, in inflated “closed” position.

FIG. 10 is a cut section of another embodiment of the present invention for installation of a plurality of interconnected tanks showing a first and a second vertical cylinder vessels each having a connection flange inside near the bottom with the first vessel inside a vertical bored underground shaft of marginally larger diameter and similar length and the second outside.

FIG. 11 is a cut section through the same embodiment of the present invention as in FIG. 10 showing the two vertical cylinder vessels inside their respective bored underground shafts of marginally larger diameters and similar lengths with their connection flanges aligned.

FIG. 12 is a cut section through the same embodiment of the present invention as in FIG. 10 showing a horizontal underground boring between the connection flanges of the two vertical cylinder vessels inside their respective bored underground shafts.

FIG. 13 is a cut section through the same embodiment of the present invention as in FIG. 10 showing a pipe sleeve inserted in the horizontal boring between the connection flanges of the two vertical cylinder vessels inside their respective bored underground shafts.

FIG. 14 is a cut section through the same embodiment of the present invention as in FIG. 10 showing a connection pressure pipe inserted inside the pipe sleeve between the connection flanges of the two vertical cylinder vessels inside their respective bored underground shafts.

FIG. 15 is a cut section through the same embodiment of the present invention as in FIG. 10 showing the fitting that connects the pressure pipe to each of the two vertical cylinder vessels.

FIG. 16 is a cut section through the same embodiment of the present invention as in FIG. 10 showing the pressure pipe connected to the second of the two vertical cylinder vessels.

FIG. 17 is a cut section through the same embodiment of the present invention as in FIG. 10 showing the pressure pipe connected to the first of the two vertical cylinder vessels.

FIG. 18 is a cut section the embodiment of the present invention for installation of a plurality of interconnected tanks showing two interconnected concrete-encased vertical cylinder vessels installed and formed inside two underground shafts.

FIG. 19 is a cut section the embodiment of the present invention for installation of a plurality of interconnected tanks showing three interconnected concrete-encased vertical cylinder vessels installed and formed inside three underground shafts.

DETAILED DESCRIPTION

FIG. 1 is a cut section of one embodiment of the present invention for installation in unsaturated soils 100 showing a prefabricated vertical cylinder vessel 101 ready for insertion inside a vertical bored underground shaft 111 of marginally larger diameter and roughly the same depth below ground 112 as the length of the vessel 101. Vertical vessel 101 and bored shaft 111 are sized to fit in a male-female fitting arrangement while leaving an annulus space as formwork for the desired thickness of concrete to be poured once vessel 101 is inserted in shaft 111. Vessel 101 is equipped with an access hatch 103 at the top that may have a smaller diameter than the diameter of the vessel 101, in which case there is a truncated cone transition 102 from the access hatch 103 to the vessel 101. If necessary, access hatch 103 may be extended with a spool of same diameter (not shown) in which case the depth of shaft 111 is increase by the same amount. The bottom 105 of the vessel 101 may be configured in the form of a sump to house a pump intake (not shown), in which case there is an inverted truncated cone transition 104 from the vessel 101 to the bottom 105.

FIG. 2 is a cut section of the same embodiment 100 of the present invention as in FIG. 1. Vertical cylinder vessel 101 is placed inside vertical bored underground shaft 111 of marginally larger diameter and roughly the same depth below ground 112 as the length of the vessel 101. Vessel 101 is supported level in vertical position on its bottom 105 with access hatch 103 at roughly the same elevation as the ground 112, leaving a roughly uniform annular space between the vessel 101 and the shaft 111.

FIG. 3 is a cut section of the same embodiment 100 of the present invention as in FIG. 2. Vertical underground storage tank 100 is comprised of a composite of inner vessel 101 and outer concrete shell 121 installed and formed in position underground inside vertical shaft 111. Tank 100 has an access hatch 103 at the top flush with ground 112. The volume of soil removed to accommodate tank 100 equals is the gross volume of the tank 100 meaning that excavation is minimized. Also, the vertical orientation of the cylindrical tank 100 means that the footprint of the tank 100 is minimized.

FIG. 4 is a cut section of another embodiment of the present invention 200 for installation in saturated soil conditions. Vertical cylinder vessel 201 is equipped with port 231 near the bottom that has an inflatable plug 241 that serves as open/close device for port 231 connected to pressure tube 242. Vertical shaft 211 is bored in saturated ground condition and is filled with groundwater 213. Vessel 201 is equipped with an access hatch 203 at the top that may have a smaller diameter than the diameter of the vessel 201, in which case there is a truncated cone transition 202 from the access hatch 203 to the vessel 201. The bottom 205 of the vessel 201 may be configured as a sump to house a pump intake (not shown), in which case there is an inverted truncated cone transition 204 from the vessel 201 to the bottom 205.

FIG. 5 is a cut section through the vessel of the same embodiment 200 of the present invention as in FIG. 4. Port 231 above transition 204 to bottom 205 of vessel 201 is equipped with inflatable plug 241 that serves as the open/close device for port 231. Inflatable plug 241 is in uninflated “open” position during installation and can be inflated to “closed” position by air tube that leads to outside of vessel 201.

FIG. 6 is a cut section through the same embodiment 200 of the present invention as in FIG. 4. Vertical cylinder vessel 201 is inserted inside bored shaft 211 while port 231 shown in FIG. 5 is “open” allowing groundwater 213 to enter inside vessel 201. Air tube 242 extends outside vessel 201 and is pressurized to close inflatable plug 241 shown in FIG. 5 once vessel 201 is in position. Vessel 201 is supported in level vertical position on its bottom 205 shown in FIG. 5 with access hatch 203 at roughly the same elevation as the ground 212, leaving a roughly uniform annular space between the vessel 201 and bored shaft 211.

FIG. 7 is a cut section through the same embodiment 200 of the present invention as in FIG. 4. Water-filled vertical cylinder vessel 201 inside bored shaft 211 has been encased in concrete 221, the vessel port 231 shown in FIG. 5 having been closed prior to pouring of the concrete in the annuls to prevent entry into vessel 201.

FIG. 8 is a cut section through the embodiment of the present invention 200 for installation in saturated soil conditions with local groundwater 213 in vessel 201 having been removed. Vertical storage tank 200 is comprised of a composite of inner vessel 201 and outer concrete shell 221 installed in position underground under saturated conditions inside vertical shaft 211 without dewatering. The tank 200 has an access hatch 203 at the top flush with ground 212. The volume of soil removed equals is the gross volume of tank 200 meaning that excavation is minimized. Also, the vertical orientation of the cylindrical tank 100 means that the footprint is minimized.

FIG. 9 is a cut section through the vessel of the same embodiment 200 of the present invention as in FIG. 8 Inflatable plug 241 has been pressurized by air tube 242 and inflated to close port 231 prior to the pouring of concrete 221. Both plug 241 and rube 242 may be removed after placement of concrete 221 and port 231 may be closed with a pipe cap (not shown).

FIG. 10 is a cut section of another embodiment 300 of the present invention for installation of a plurality of interconnected tanks. There is a first vertical cylinder vessel 301 placed inside vertical bored shaft 311 below ground 312 and a second vertical cylinder vessel 301 outside vertical bored shaft 312 ready for placement. Both vessels 301 and 302 are equipped with connection flanges 331 and 332 located near the bottom that are accessed and connect from inside the vessels 301 and 302. The bottom 306 of second vessel 302 may be of same diameter as vessel 302 since first vessel 301 has an inverted truncated cone transition 304 from vessel 301 to bottom 305 that creates a sump for removal of fluids from both vessels 301 and 302.

FIG. 11 is a cut section through the same embodiment 300 of the present invention as in FIG. 10. Both the first vertical cylinder vessel 301 and the second vertical cylinder vessel 302 are inside their respective bored vertical shafts 311 and 302, with their connection flanges 331 and 331 aligned.

FIG. 12 is a cut section through the same embodiment 300 of the present invention as in FIG. 10. There is a horizontal underground boring 351 between the connection flanges 331 and 332 of the two vertical cylinder vessels 301 and 302 inside their corresponding bored underground shafts 311 and 312. Horizontal underground boring techniques is used for trenchless pipe laying in water, sewer, and gas pipeline industries and is widely available.

FIG. 13 is a cut section through the same embodiment 300 of the present invention as in FIG. 10. There is a pipe sleeve 352 inserted in the horizontal boring 351 shown in FIG. 12 between the connection flanges 331 and 332 of the two vertical cylinder vessels 301 and 302 inside their corresponding bored underground shafts 311 and 312.

FIG. 14 is a cut section through the same embodiment of the present invention as in FIG. 10. Pressure pipe 353 is inserted inside pipe sleeve 351 shown in FIG. 12 between the connection flanges 331 and 332 of the two vertical cylinder vessels 331 and 332 inside their corresponding bored underground shafts 311 and 312.

FIG. 15 is a cut section through the same embodiment 300 of the present invention as in FIG. 10. Female fitting 354 tightly fits male connection pipe 353 and has a flange that matches connection flange 332 inside second vessel 302. There an identical fitting arrangement for first vessel 301 on the far side (not shown).

FIG. 16 is a cut section through the same embodiment 300 of the present invention as in FIG. 10. Pressure pipe 353 shown in FIG. 15 is connected to second vertical cylinder vessel 302 via female fitting 354 sealed against connection flange 332 inside second vessel 302 and pressure pipe 353 shown in FIG. 15.

FIG. 17 is a cut section through the same embodiment 300 of the present invention as in FIG. 10. Pressure pipe 353 shown in FIG. 15 is connected to first vertical cylinder vessel 301 via female fitting 354 sealed against connection flange 331 inside second vessel 301 and pressure pipe 353 shown in FIG. 15. First vertical cylinder vessel 301 and second vertical cylinder vessel 302 are fully sealed from outside environment while being interconnected via pressure pipe 353 shown in FIG. 15 and function as a single underground storage facility.

FIG. 18 is a cut section the embodiment of the present invention comprising of a plurality of interconnected underground storage tanks 300. There are two interconnected vertical cylinder vessels 301 and 302 installed inside two underground vertical shafts 301 and 302 and encased in concrete 321. The tanks function as a single sealed storage facility below ground 312.

FIG. 19 is a cut section the embodiment of the present invention comprising of a plurality of interconnected underground tanks 300. There are three interconnected vertical cylinder vessels 301, 302, and 303 installed inside three underground vertical shafts 311, 312, and 313, encased in concrete 321. The tanks function as a single sealed storage facility below ground 312. In this manner, the number of tanks can increase as needed to fit the storage requirements and site conditions.

In some situations it may be necessary to pour the concrete immediately after placement of the vessel inside the shaft. If so, then the connection flanges 301 and 302 of FIG. 10 are equipped with an inflatable plug 241 of FIG. 9, which is “closed” during pouring of concrete to prevent its entry into the vessel and removed once the concrete is set. In such cases, the steps shown in FIG. 12 through FIG. 18 are carried out without change with the concrete encasement in place.

For installations in saturated ground conditions the steps shown in FIG. 4 through FIG. 8 is carried out to install and form each individual vessel, and is followed by the steps shown in FIG. 12 through FIG. 18 to connect the vessels.

The present invention is susceptible to modifications and variations which may be introduced thereto without departing from the inventive concepts and the object of the invention. Other elements such and ports, piping, access means, fittings, and valves may be added to the vessels to accommodate the specific needs of a site. The diameter of depth of the vertical shafts that accommodate the vessels may be varied to exceed the diameter and length of the vessel as necessary.

While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is to be understood that the present invention is not to be limited to the disclosed arrangements, but is intended to cover various arrangements which are included within the spirit and scope of the broadest possible interpretation of the appended claims so as to encompass all modifications and equivalent arrangements which are possible. 

I claim:
 1. A composite-material underground storage tank for storage of fluids, the tank comprising: an enclosed cylindrical vessel vertically oriented with one circular end at the top and the other circular end at the bottom said vessel comprising the interior surface and inner layer of said composite-material underground storage tank; a vertical bored shaft in the ground having a diameter larger than the outside diameter of said cylindrical vessel and depth below ground of at least equal to the length of the said cylindrical vessel, said bored shaft housing the said cylindrical vessel such that the annular space between the outside perimeter of said cylindrical vessel and inside perimeter of said vertical shaft is nearly uniform around, said vertical bored shaft also serving as the formwork for the in-situ forming of the exterior layer of said underground storage tank; in-situ poured concrete that occupies said annular space between said cylindrical vessel and said vertical bored shaft, said concrete comprising the exterior surface and the outer layer of said composite-material underground storage tank; means of access from ground surface into the interior of said cylindrical vessel via said circular end at the top.
 2. The underground storage tank of claim 1 further comprising a port near the bottom of said vessel accessed and operated from inside said cylindrical vessel fitted with a means of opening and closing said port that is operated from exterior of said cylindrical vessel at ground level.
 3. The underground storage tank of claim 2 wherein the said port is further fitted with a means of establishing a sealed connection with a pressure pipe that extends horizontally out and beyond said vertical bored shaft.
 4. A plurality of interconnected composite-material underground storage tanks for storage of fluids, comprising: a plurality of enclosed cylindrical vessels vertically oriented each with one circular end at the top and the other circular end at the bottom, said vessels comprising the interior and the inner layer of said composite-material underground storage tanks; a plurality of vertical bored shafts in the ground corresponding to said vertical vessels having diameters larger than the outside diameters of their respective said cylindrical vessels and depths below ground of at least equal to the lengths of their respective said cylindrical vessels, housing the said cylindrical vessels such that the annular spaces between the outside perimeters of said cylindrical vessels and inside perimeters of said vertical shafts are nearly uniform; in-situ poured concrete that occupies the said annular spaces between said cylindrical vessels and said vertical bored shafts comprising the exterior surface and the outer layer of said composite-material underground storage tanks; at least one access from ground surface into interior of said cylindrical vessels via at least one said circular end at the top of one of said vertical vessels; at least one port on the inside of and near the bottom of each and every one of said cylindrical vessels capable of being fitted with a means of opening and closing of said ports from exterior of said cylindrical vessels at ground level plus means of establishing a sealed connection with a pressure pipe that extends horizontally out and connects to at least one of the said plurality of vessels. 